Effects of liberal versus restrictive transfusion strategies on intermittent hypoxaemia in extremely low birthweight infants: secondary analyses of the ETTNO randomised controlled trial.

Objectives: To compare the effect of liberal versus restrictive transfusion strategies on the proportion of time (%time) spent with intermittent hypoxaemia (IH, ie, arterial haemoglobin oxygen saturation measured by pulse oximetry (SpO₂) <80% lasting ≥60 s) in the 'Effects of Transfusion Thresholds on Neurocognitive Outcome' (ETTNO) population, and to investigate whether infants with above-median exposure to IH might benefit more from liberal transfusion strategies than those with lower exposure.

Design, setting, patients: Secondary analysis in all 554/1013 infants of <1000 g birth weight recruited into the ETTNO trial (mean gestational age 26.2 weeks) with >80% completeness of SpO₂ recordings during postnatal days 8-49.

Intervention: Randomly assigned liberal (n=268) or restrictive (n=286) transfusion strategies, defining transfusion triggers based on postnatal age and health status.

Main outcome measures: %time with IH, rate and mean duration of IH episodes during postnatal days 8-49. Interaction between exposure to IH and transfusion strategies with respect to ETTNO's composite primary outcome, death or disability at 24 months corrected age.

Results: The median (quartile 1-quartile 3) %time with IH was similar between treatment groups (0.91% (0.13%-2.83%) with liberal vs 0.79% (0.16%-2.44%) with restrictive transfusions). There was no interaction between exposure to IH and transfusion strategies on outcome at 24 months.

Conclusions: In infants <1000 g birth weight, a liberal transfusion strategy did not reduce IH. Blood transfusions should not be administered 'liberally' to reduce IH or to improve neurocognitive outcome in infants with above-average exposure to IH.

Trial registration number: NCT01393496.